Sorry, found that I never posted the resolution to my issue here. After getting several suggestions, I had found another story (on another site) where user had exact same problem. Ends us simpler, and cheaper than thought. Again, symptoms seem to be that the car had to actually sit for a few days to make this happen, which is why it only happened on 3 successive Mondays. In other users case, was found to be the distributor. I talked to my mechanic, who did NOT believe that to be the issue. But agreed it had very slight chance to be the problem, and agree to change it since it was a cheap repair and probably needed to be done anyway due to age (was about $100-150 I think). Since replacement, have not had another single issue...at least not like this one. Seems that it was the distributor after all, and not idle control valve or fuel pump relay. Hope this info helps someone else...